Needle cooling device for sewing machines



Sept 28, 1954 F. w. ADAMS NEEDLE COOLING DEVICE FOR SEWING MACHINES Filed Feb. 7, 1950 SOURCE OF COOLING MEDIUM ONDER PRESSURE INVENTOR FREDERICK W. HDHMS BY 25M/144] @M YM ATTO R N EYS Patented Sept. 28, 1954 NEEDLE COOLING DEVICE FOR SEWING MACHINES l'red erick Adams, New `Kork, N. Y., assigner to Goats & Clark Inc., a corporation of Delaware Application February 7, 1950 Serial No. 142,927

(Cl. i12-218) 2 Claims. 1

The present invention relates to4 improvements in needle cooling -devices and relates more particularly to a device for continuously cooling the needle in a sewing machine.

The present invention provides ffor the application of a `plurality of jets of 'a cooling medium at high velocity directly to the eye of a needle during the sewing operation. By applying high velocity jets of the cooling medium continuously 'to the eye of the needle, lan effective transfer of heat is obtained between the needle and the cooling medium not only during thel sewing, but also during the time when the needle i-s at a standstill. IIhe various objects and advantages of the present invention will be apparent and best understood from the following description and the accompanying drawings, in which:

Fig. 1 is an end view in partial section of a needle cooling device embodying the invention; and

Fig. 2 is a bottom view of the needle cooling device illustrated in Fig. 1

Referringnow to the drawings, Fig. 1 illustrates the end of a sewing machine head 'l in which a hollow needle bar 2 is. mounted. The needle bar 2 is in the form of a tube and is slidably supported in the head l in spaced bearings. The needle bar 2 is reciprocated vertically in the sewing machine head l during the sewing operation in the usual manner by suitable mechanism (not shown).

In the illustrated embodiment, the upper bearing for the needle bar 2 consists of a fitting or sleeve 3 that is threaded to the head l and into which the upper end o'f needle bar 2 is slidably lltted. A coupling 4 is supported on the fitting 3 by studs 5 with the lower end 6 of the coupling extending into the upper end of the needle bar 2. The lower end 6 of the coupling 4 makes a sliding t inside of the needle `bar 2 and extends into the end of the needle bar a suitable distance to form 'a seal during reciprocation of the needle bar 2. The upper end 'l of the coupling 4 receives the end of a tube 8 of suitable material. The tube 8 may lbe made of rubber and it connects the hollow needle bar to a source of a cooling medium under pressure such as air which may be supplied from an air compressor.

For the purposes of the following description ,air will be referred 'to as the cooling medium, but it will be understood that a coolant such as water in atomized form may be injected into the cooling air, or other suitable coolants may be employed if desired. A lubricant may also be added to the cooling air so as to lubricate the thread in order 'fto facilitate the sewing operation. It has been `found that in sewing vcertain goods such as plastics and/or when sewing lwith synthetic thread such as nylon, the addition of such lubrication materially assists the sewability and reduces heat fromA the friction of 'the thread passing through the eye of the needle.

As shown in Fig. 1, the fitting 3 may be recessed to provide a passageway as indicated at 9 surrounding the connection of the needle bar 2 with the coupling `4. The passageway 9 communicates with vents l0 in the coupling support that permit any of the cooling air that escapes between the coupling and the needle bar to pass from the head. However, the cooling air may be supplied under pressure to the needle bar 2 by attaching the iiexible, rubber 'tube 3 directly to the upper end of the hollow needle bar. Also, in types of sewing machines where the needle bar does not protrude above the top of the sewing machine head, the cooling air may be admitted under pressure to the needle bar through a suitable port o r slide valve located within the head.

The hollow needle bar 2 permits the cooling air to pass through it without a substantial drop in pressure to the lower end of the needle bar 2 where a needle H is supported in a chuck l2. The c hucl: I2 is iitted within the opening lat the lower end of the hollow needle bar 2 and is provided lwith a receptacle to receive the needle l i. The needle I I may be held in place 'by a set screw I3 that extends through 'the needle bar and the chuck with its end bearing against the shank of the needle l l when tightened, 'as shown in Fig. 2.

The chuck I2 is provided with a plurality or inclined passageways M that are spaced about the needle Il supported therein. The passageways I4 are each inclined at an angle Iwhich directs .a high velocity jet of the cooling air that is contained under ipressure in the needle bar downwardly so that the jets impinge directly upon the eye of the needle ll as indicated by the arrows in. Fis. 1. By the term high velocity, a velocity is meant where a turbulent movement of the cooling air in the jet is obtained. When such a high velocity jet strikes the needle `at the eye thereof, the turbulent movement of the cooling air in the jet results in a highly eiective and rapid heat transfer between the needle and the ycooling air. A turbulent movement of the cooling lair in the jets may be obtained at velocities having the equi-valent of a Reynold number of approximately 2300 or above (when measured in consistent units) To obtain the -desired velocity of the jets using air under pounds pressure per square inch, the passageways I4 are m-ade relatively small in diameter with 'their length being suicient to project `the cooling air in a stream of uniform cross-section to the point Where it impinges on the eye of the needle. The diameter of the ypa'ssageways I4 may be as small `as can be drilled conveniently and their length s-hould be approximately ve times their diameter. Although these values are not critical, the pressure drop produced will be too great if the ipassageways are made too long, but on the other hand they will not serve properly to direct the jets to 'the eye of the needle if they are made too short.

In the illustrated embodiment of the invention the hollow needle ybar 2 and 'the chuck l2 form a 4chamlbered member which is connected to and reciprocates with the needle l'l. Thus, the converging jets of cooling medium emerging from the inclined outlet ypassageways I4 are at all times directed at the eye of 'the needle and this critical point where the needle contacts `with the thread is continuously cooled thereby.

In accordance with the present invention the high velocity jets of the cooling air impinge directly upon the eye of the needle which is the point where frictional enerei7 due to penetration of the fabric being sewn is developed and where the maximum temperature of the needle occurs. Therefore, the desired cooling is obtained at the source of the heat and the needle temperature is substantially reduced during the sewing operation.

When the needle penetrates the fabric the jets discharge the lai-r along the needle shaft against the fabric at a point where the stitch will be drawn up. In heavy sewing operations at high speed, needle temperatures may run between S50-600 F., if no cooler is employed. Use of the present cooler using yair at 10 pounds per square inch pressure has been found to reduce the 'temperature at the needle eye by about 250 F. In normal sewing operations through heavy goods, when the needle is withdrawn from the goods at a machine stoppage the high temperature of the needle may readily cause fusing or vweakening of synthetic threads, because the rate of cooling oi' the needle in still air is slow and the thread lays against the yhot needle for a considerable period of time. It is impossible to touch a needle stopped under these conditions without 'burning ones ngers. When however the present needle cooler is used `and the sewing machine stops with the needle above the fabric, the rate of cooling is extremely rapid so that the needle ymay be immediately grasped between the thumb yand iorenger without any sensation of warmth from the needle. Attempts to measure this rate of cooling indicate that the needle reaches a temperature below 150 F. in less than two seconds and probably within a fraction of a second. This is very important -When sewing with thread made of synthetics such as nylon because most breaks due to fusing or weakening of the thread occur when the machine is stopped and the needle is retracted from the goods.

The needle cooler of the present invention not only assists in the sewing of synthetic threads, but i-t also prevents 'the fusing or weakening of synthetic fabrics which are being sewn and which are readily ldamaged by a hot needle.

It will be understood that various modications and changes vmay be made in the illust-rated embodiment o'f the invention without departing from the scope of the invention as defined by the following claims.

I claim:

1. In a device for continuously cooling a needle of a sewing machine, the combination which includes a hollow needle bar mounted for vertical reciprocation in a head of a sewing machine, said needle lbar having an upper end and a lower end yand being open at its upper end, a coupling for connecting the `upper end of the needle bar to a source of a cooling medium under pressure and including a sleeve mounted in a fixed position on the head of the sewing machine, said sleeve being open at its ends Iand having one end slidably fitted within the open end of the needle bar, and a tubular member connecting the other end of the sleeve to the source of the cooling medium.

2. A device for continuously cooling a needle of a sewing machine which comprises a hollow needle bar mounted for vertical reci-procation in the head of a `sewing machine, said needle Ibar having an upper end and a lower end with a chamber connecting the upper and lower ends thereof, coupling means for connecting the hollow needle bar lto a source of a cooling medium under pressure, said coupling means comprising a xed `member mounted on the head o the .sewe ing machine, :said fixed member including a sleeve, said sleeve being open at its ends and having one end `slidably tted within the upper end of the needle bar and its other end connected to the source of the cooling medium, a needle holding chuck located at the lower end of the needle bar, said chuck having a plurality of inclined passageways therein, said passageways being spaced relative to each other and being inclined at an angle with respect to the axis of the needle lbar to direct converging jets of the cooling medium toward a point located beyond the lower end of the needle bar and the needle holding chu-ck.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,097,403 Eichhorn May 19, 1914 1,686,439 `Cooke Oct. 2, 1922 2,418,429 Sauer Apr. l, 1947 2,418,483 Runcie Apr. 8, 1947 2,442,033' Brantley et al May 25, 1948 2,593,203 lSchwartz Apr. 15, 1952 

